Self-healing metal composite tube walls

ABSTRACT

A tubular structure including an outer tube an inner tube arranged within the outer tube and at least one chamber formed between the outer tube and the inner tube. The tubular structure additionally includes at least one self-healing material arranged in the chamber, wherein the self-healing material is configured to solidify and/or expand upon contact with a reacting material.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of parent U.S. applicationSer. No. 15/639,190 filed on Jun. 30, 2017, and claims the benefit ofU.S. Provisional Application No. 62/358,696 filed on Jul. 6, 2016, thedisclosures of which are expressly incorporated by reference herein intheir entireties.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present disclosure relates to the repairing of small holes within anenclosed structure without human intervention, and more specifically, toself-healing metal composite tube walls.

2. Background of the Disclosure

A transportation system used to transport an object may comprise atubular structure. One method of constructing such a tubular structureis to weld an inner tube to an outer tube, thus creating an enclosedchamber that acts as a buffer between an outer, uncontrolled environmentthat the outer tube is subject to and an inner, controlled environmentthat the inner tube maintains. A problem that arises with thisstructural design is responding to a puncture in the outer tube. Apuncture can be especially problematic if the hole also pierces theinner tube and threatens the inner, controlled environment.

Additionally, when exposed for long times to high temperatures andmoderate stresses, metals may exhibit premature and low-ductility creepfracture, arising from the formation and growth of cavities. Thosedefects may coalesce into cracks which ultimately cause macroscopicfailure.

In general, cracks or punctures may be hard to detect at an early stage,and manual intervention is required for periodic inspections andrepairs, which can incur large costs. For example, upon detecting ahole, the hole may be remedied by manual repair. On site manual repair,however, may be too costly, and depending on the location of the tube,may be too dangerous. Additionally, such a manual repair may requireshutting down the transportation system (or portions thereof) at greatcost.

Therefore, there is a need in the art for an approach to quickly patch aleak in such a tubular double wall structure without requiring manualintervention or action (at least until further maintenance can beperformed).

SUMMARY OF THE EMBODIMENTS OF THE DISCLOSURE

The novel features which are characteristic of the disclosure, both asto structure and method of operation thereof, together with further aimsand advantages thereof, will be understood from the followingdescription, considered in connection with the accompanying drawings, inwhich the preferred embodiment of the disclosure is illustrated by wayof example. It is to be expressly understood, however, that the drawingsare for the purpose of illustration and description only, and they arenot intended as a definition of the limits of the disclosure.

Aspects of the present disclosure are directed to a tubular structurecomprising: an outer tube; an inner tube arranged within the outer tube;at least one chamber formed between the outer tube and the inner tube;and at least one self-healing material arranged in the chamber, whereinthe self-healing material is configured to solidify and/or expand uponcontact with a reacting material.

In embodiments, the tubular structure further comprises at least twochamber separators, wherein the at least one chamber comprises aplurality of chambers formed by the at least two chamber separators.

In some embodiments, wherein the chamber separators extend in a radialdirection between the inner tube and the outer tube and extendlongitudinally along the inner tube.

In additional embodiments, the chamber separators extend in a radialdirection between the inner tube and the outer tube and extendcircumferentially along the inner tube.

In further embodiments, the at least one self-healing material isarranged in discrete portions in each of the plurality of chambers.

In embodiments, the reacting material is at least one foreign fluid.

In some embodiments, the at least one self-healing material comprisesfirst and second self-healing materials, wherein the first self-healingmaterial is configured to solidify upon contact with a first foreignfluid, and the second self-healing materials is configured to solidifyupon contact with a second foreign fluid.

In additional embodiments, the first foreign fluid is external to theouter tube, and wherein the second foreign fluid is internal to theinner tube.

In further embodiments, the reacting material is arranged in proximityto the self-healing material, while being maintained isolated from theself-healing material by an isolating material.

In some embodiments, the isolating material is operable to dissolve,degrade, disintegrate, and/or breakdown upon contact with a foreignfluid.

In embodiments, the inner tube is concentrically arranged within theouter tube.

In additional embodiments, the at least one self-healing material isstructured and arranged to be contacted with a foreign fluid enteringthe at least one chamber through a hole formed in a wall of the outertube, and upon the solidification and/or expansion of the self-healingmaterial, forms a solidified section that seals the hole.

In further embodiments, the at least one self-healing material isconfigured such that the solidified section formed therefrom expands tocontact both the outer tube and the inner tube.

In embodiments, the at least one self-healing material is configuredsuch that a solidified section formed therefrom expands to contact boththe outer tube and the inner tube and a plurality of chamber separators.

In some embodiments, the self-healing material is encapsulated in anenclosing material.

In additional embodiments, the at least one self-healing material isstructured and arranged to be contacted with a foreign fluid enteringthe at least one chamber through a hole formed in a wall of the innertube, and upon the solidification and/or expansion of the self-healingmaterial, forms a solidified section that seals the hole.

In embodiments, the self-healing material comprises at least one ofpolymers, elastomers, metals, ceramics, cementitious materials, andgrout materials.

Additional aspects of the present disclosure are directed to a method offorming a tubular structure comprising an outer tube, an inner tubearranged within the outer tube, and at least one chamber formed betweenthe outer tube and the inner tube. The method comprises forming the atleast one chamber and arranging at least one self-healing material inthe at least one chamber, wherein the self-healing material isconfigured to solidify and/or expand upon contact with a reactingmaterial.

Further aspects of the present disclosure are directed to a method ofsealing a hole in a tubular structure comprising an outer tube, an innertube arranged within the outer tube, at least one chamber formed betweenthe outer tube and the inner tube, and at least one self-healingmaterial arranged in the at least one chamber, wherein the self-healingmaterial is configured to solidify and/or expand upon contact with areacting material. The method comprises contacting the self-healingmaterial with the reacting material such that the self-healing materialsolidifies and/or expands to form a solidified section and sealing thehole with the solidified section.

In embodiments, the contacting the self-healing material with thereacting material occurs by the reacting material flowing through thehole.

In some embodiments, the contacting the self-healing material with thereacting material comprises: a foreign fluid entering the at least onechamber through the hole; and dissolving, degrading, disintegrating,and/or breaking down a isolating material arranged between theself-healing material and the reacting material using the foreign fluidentering through the hole so that the self-healing material interactswith the reacting material.

In additional embodiments, the hole is formed in the outer tube.

In further embodiments, the hole is formed in the inner tube.

The present disclosure is related to a system that utilizes sealing (orhealing) materials, reactive to the presence or lack of presence of aspecific fluid/material, such as water or air. In embodiments, thematerial can also be modified (or selected) depending on the outerenvironment (e.g., desert vs. arctic environment). In embodiments, thesealing (or healing) materials may be air-curing and/or water-curingepoxies, polymers, gels, concretes, grouts and/or rubbers. Otherexemplary sealing (or healing) materials include sealing materials usedin quick-application sealants for bike tubes.

By implementing aspects of the disclosure, repairs to the tube structuremay be achieved remotely without manual intervention and without thecosts involved with manual repair. Additionally, by implementing aspectsof the disclosure, utilizing a material that can intrinsically correctdamage caused by e.g., normal usage may prevent costs incurred bymaterial failure and/or lower costs of a number of different industrialprocesses through longer part lifetime, and reduction of inefficiencycaused by degradation over time. Thus, in accordance with aspects of thedisclosure, self-healing of early stage damage is thus a promisingapproach to extend the lifetime of the metallic components.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of this disclosure will be best understood byreference to the following detailed description of embodiments of thedisclosure, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 shows an exemplary tube structure in accordance with aspects ofthe disclosure;

FIG. 2 shows a hole in the tube structure with a fluid entering achamber of the tube structure in accordance with aspects of thedisclosure;

FIG. 3 shows the hole in the tube structure extending completely throughthe tube structure in accordance with aspects of the disclosure;

FIG. 4 shows the tube structure with a self-healing material inaccordance with aspects of the disclosure;

FIG. 5 shows the fluid entering the chamber through the hole andcontacting the self-healing material in accordance with aspects of thedisclosure;

FIG. 6 shows the sealing (or hole-repairing) material solidifying uponcontacting the fluid in accordance with aspects of the disclosure;

FIG. 7 shows the sealing (or hole-repairing) self-healing materialexpanding to provide structural support in accordance with aspects ofthe disclosure;

FIG. 8 shows a second exemplary tube comprising a plurality of chamberseparators and the self-healing material in accordance with aspects ofthe disclosure;

FIG. 9 shows the second tube with the hole in the tube structure andfluid entering the chamber through the hole in accordance with aspectsof the disclosure;

FIG. 10 shows the fluid contacting the self-healing material and theself-healing material reacting to the fluid in accordance with aspectsof the disclosure;

FIG. 11 shows the self-healing material expanding and solidifying toform a vacuum seal in accordance with aspects of the disclosure; and

FIG. 12 shows the self-healing material expanding to provide structuralsupport in accordance with aspects of the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE DISCLOSURE

In the following description, the various embodiments of the presentdisclosure will be described with respect to the enclosed drawings. Asrequired, detailed embodiments of the embodiments of the presentdisclosure are discussed herein; however, it is to be understood thatthe disclosed embodiments are merely exemplary of the embodiments of thedisclosure that may be embodied in various and alternative forms. Thefigures are not necessarily to scale and some features may beexaggerated or minimized to show details of particular components.Therefore, specific structural and functional details disclosed hereinare not to be interpreted as limiting, but merely as a representativebasis for teaching one skilled in the art to variously employ thepresent disclosure.

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present disclosureonly and are presented in the cause of providing what is believed to bethe most useful and readily understood description of the principles andconceptual aspects of the present disclosure. In this regard, no attemptmay be made to show structural details of the present disclosure in moredetail than is necessary for the fundamental understanding of thepresent disclosure, such that the description, taken with the drawings,making apparent to those skilled in the art how the forms of the presentdisclosure may be embodied in practice.

As used herein, the singular forms “a,” “an,” and “the” include theplural reference unless the context clearly dictates otherwise. Forexample, as used herein, the indefinite article “a” indicates one aswell as more than one and does not necessarily limit its referent nounto the singular. Thus, for example, reference to “a magnetic material”would also indicate that mixtures of one or more magnetic materials canbe present unless specifically excluded.

Except where otherwise indicated, all numbers expressing quantities usedin the specification and claims are to be understood as being modifiedin all instances by the term “about.” Accordingly, unless indicated tothe contrary, the numerical parameters set forth in the specificationand claims are approximations that may vary depending upon the desiredproperties sought to be obtained by embodiments of the presentdisclosure. At the very least, and not to be considered as an attempt tolimit the application of the doctrine of equivalents to the scope of theclaims, each numerical parameter should be construed in light of thenumber of significant digits and ordinary rounding conventions.

Additionally, the recitation of numerical ranges within thisspecification is considered to be a disclosure of all numerical valuesand ranges within that range (unless otherwise explicitly indicated).For example, if a range is from about 1 to about 50, it is deemed toinclude, for example, 1, 7, 34, 46.1, 23.7, or any other value or rangewithin the range.

As used herein, the terms “about” and “approximately” indicate that theamount or value in question may be the specific value designated or someother value in its neighborhood. Generally, the terms “about” and“approximately” denoting a certain value is intended to denote a rangewithin ±5% of the value. As one example, the phrase “about 100” denotesa range of 100±5, i.e. the range from 95 to 105. Generally, when theterms “about” and “approximately” are used, it can be expected thatsimilar results or effects according to the disclosure can be obtainedwithin a range of ±5% of the indicated value.

The term “at least partially” is intended to denote that the followingproperty is fulfilled to a certain extent or completely.

The terms “substantially” and “essentially” are used to denote that thefollowing feature, property or parameter is either completely (entirely)realized or satisfied or to a major degree that does not adverselyaffect the intended result.

The term “substantially parallel” refers to deviating less than 20° fromparallel alignment and the term “substantially perpendicular” refers todeviating less than 20° from perpendicular alignment. The term“parallel” refers to deviating less than 5° from mathematically exactparallel alignment. Similarly “perpendicular” refers to deviating lessthan 5° from mathematically exact perpendicular alignment.

The term “comprising” as used herein is intended to be non-exclusive andopen-ended. Thus, for instance a composition comprising a compound A mayinclude other compounds besides A. However, the term “comprising” alsocovers the more restrictive meanings of “consisting essentially of” and“consisting of,” so that for instance “a composition comprising acompound A” may also (essentially) consist of the compound A.

As used herein, the term “and/or” indicates that either all or only oneof the elements of said group may be present. For example, “A and/or B”shall mean “only A, or only B, or both A and B”. In the case of “onlyA”, the term also covers the possibility that B is absent, i.e. “only A,but not B.”

The various embodiments disclosed herein can be used separately and invarious combinations unless specifically stated to the contrary.

Embodiments of the present disclosure may be used in a transportationsystem, for example, as described in commonly-assigned application Ser.No. 15/007,783, entitled “Transportation System,” the contents of whichare hereby expressly incorporated by reference herein in their entirety.Additionally, embodiments of the present disclosure may utilize a tubeconstruction, for example, as described in commonly-assigned applicationSer. No. 15/374,230, entitled “Method and System for Forming Laser BeamWeld Lap-Penetration Joints,” the contents of which are hereby expresslyincorporated by reference herein in their entirety.

FIG. 1 shows an exemplary tube structure 1 in accordance with aspects ofthe disclosure. With this exemplary embodiment, the tube structure 1comprises an inner tube 2 and an outer tube 3. In embodiments, the innertube 2 and the outer tube 3 may comprise metal (e.g., steel). Inembodiments, the tube 2 and tube 3 may be welded together (e.g., viaradially extending connections welded between tube 2 and tube 3). Inother contemplated embodiments, the tubes can be joined without welds(e.g., joined with adhesives, fasteners, etc.). Arranged between theinner tube 2 and the outer tube 3 is an enclosed chamber 5. The outershell (or surface) of the outer tube 3 is exposed to an uncontrolledenvironment. Depending upon where the tube structured 1 is situated, inembodiments, the uncontrolled environment may include, for example,ambient air, an underwater salt water environment, or an underwaterfresh water environment, amongst other contemplated environments. Theinner shell (or surface) of the inner tube 2 is exposed to a controlledenvironment 4 (e.g., a low-pressure or vacuum environment). The enclosedchamber 5 has an internal environment therein.

In accordance with aspects of the disclosure, one purpose of thisdouble-wall structure having the enclosed chamber 5 is to prevent thecontrolled environment 4 from coming into contact with the uncontrolledenvironment and to keep the internal environment within the chamber 5from coming into contact with either of the controlled environment 4 orthe uncontrolled environment.

FIG. 2 shows the tube structure 1 with a hole 7 formed in the outer tube3. For example, the hole 7 may be caused by a projectile (e.g., abullet) striking the outer tube 3. With this exemplary embodiment, thetube structure 1 is arranged in an uncontrolled environment of fluid 9(e.g., seawater). As shown in FIG. 2, the hole 7 in the outer tube 3exposes the chamber 5 to the uncontrolled environment comprising a fluid9. Due to the relatively higher pressure of the uncontrolled environment(as compared to the lower pressure of the chamber 5), fluid 9 enters thechamber 5 through the outer hole 7. Such a situation may negativelyimpact the tube structure 1. For example, having fluid enter the chamber5 may impact the buoyancy characteristics of the tube structure 1 and/orimpact the weight distribution of the tube structure 1.

FIG. 3 shows the tube structure 1 with both a hole 7 in the outer tube 3and a hole 8 in the inner tube 2. With such a defect, the fluid 9travels from the outer, uncontrolled environment, through hole 7, thenthrough the chamber 5 and the inner hole 8 into the controlledenvironment 4. That is, due to the relatively higher pressure of theuncontrolled environment (as compared to the lower pressure of thechamber 5), fluid 9 enters the chamber 5 through hole 7. Due to therelatively higher pressure of the chamber 5 (as compared to the lowerpressure of the controlled environment 4), fluid 9 enters the controlledenvironment 4 through hole 8. Such a situation may negatively impact thetube structure 1. For example, in addition to the negative impacts ofthe fluid in chamber 5, discussed above, with hole 8, the fluid 9 wouldenter into the controlled environment 4 impacting the ability for thecontrolled environment 4 to allow for passage of a transportationvehicle.

FIG. 4 shows how the tube structure 1 may further comprise aself-healing material (SHM) 11 located within the chamber 5 between theinner tube 2 and the outer tube 3 in accordance with aspects of thedisclosure. In embodiments, self-healing materials may includeartificial or synthetically-created substances that possess the abilityto automatically repair damage to themselves (or adjacent materials)without any external diagnosis of the problem or human intervention.

As noted, materials of the tube wall may be purposefully damaged (e.g.,bullet holes), accidentally damaged, and/or may degrade over time dueto, e.g., fatigue, environmental conditions, or damage incurred duringoperation. Cracks and other types of damage on a microscopic level havebeen shown to change thermal, electrical, and acoustical properties ofmaterials, and the propagation of cracks can lead to eventual failure ofthe material. If the material of the outer tube wall or inner tube wallfails, the tube structure or the transportation system utilizing thetube structure may likewise fail.

In general, cracks may be hard to detect at an early stage, and manualintervention may be required for periodic inspections and repairs. Incontrast, self-healing materials counter degradation through theinitiation of a repair mechanism that responds to damage (e.g.,micro-damage). Some self-healing materials are classified as smartstructures, which can adapt to various environmental conditionsaccording to their sensing and/or actuation properties.

Although the most common types of self-healing materials are polymers orelastomers, self-healing covers all classes of materials, includingmetals, ceramics, cementitious materials, and grout materials.

The healing mechanisms of self-healing materials can vary from anintrinsic repair of the material to the addition of a repair agentcontained in, e.g., in a vessel, such as a microscopic vessel. For amaterial to be strictly defined as autonomously self-healing, thehealing process should occur without human intervention. Self-healingpolymers may, however, activate in response to an external stimulus(fluid contact, pressure change, temperature change, etc.) to initiatethe healing process.

Polymer materials can be divided into two different groups based on theapproach to the self-healing mechanism: intrinsic or extrinsic.Autonomous self-healing polymers may follow a three-step process. In theevent of damage, the first response is triggering or actuation, whichhappens almost immediately after damage is sustained. The secondresponse is transport of materials to the affected area, which alsohappens very quickly. The third response is the chemical repair process.This process differs depending on the type of healing mechanism that isin place (e.g., polymerization, entanglement, reversible cross-linking).These self-healing materials can be classified in three different ways:capsule-based, vascular, and intrinsic. While similar in some ways,these three ways differ in the ways that response is hidden or preventeduntil actual damage is sustained.

In intrinsic systems, the healing material is able to restore itsintegrity. While extrinsic approaches are generally autonomous,intrinsic systems often require an external trigger for the healing totake place (such as thermo-mechanical, electrical, photo-stimuli, etc.).One strategy achieves the self-healing in thermoset matrices byincorporating meltable thermoplastic additives. A temperature triggerallows the re-dispersion of thermoplastic additives into cracks, givingrise to mechanical interlocking.

In extrinsic systems, the healing chemistries are separated from thesurrounding polymer in, for example, microcapsules or vascular networks,which after material damage/cracking release their content into thecrack plane, reacting and allowing the restoration of materialfunctionalities. These systems can be further subdivided in severalcategories. While capsule-based polymers sequester the healing agents inlittle capsules that only release the agents if they are ruptured,vascular self-healing materials sequester the healing agent incapillary-type hollow channels, which can be interconnected onedimensionally, two dimensionally, or three dimensionally. After one ofthese capillaries is damaged, the network can be refilled by an outsidesource or another channel that was not damaged.

Methods for the implementation of self-healing functionality into filledcomposites and fiber-reinforced polymers (FRPs) can be broadlyclassified into two approaches; discrete capsule-based systems andcontinuous vascular systems.

In embodiments, the self-healing material may be in the form of acoating. Coatings allow the retention and improvement of bulk propertiesof a material. They can provide protection for a substrate fromenvironmental exposure. Thus, when damage occurs (often in the form ofmicro-cracks), environmental elements like water and oxygen can diffusethrough the coating and may cause material damage or failure.Micro-cracking in coatings can result in mechanical degradation ordelamination of the coating, or in electrical failure infiber-reinforced composites and microelectronics, respectively. As thedamage is on such a small scale, repair, if possible, is often difficultand costly. Therefore, a coating that can automatically heal itself(“self-healing coating”) could prove beneficial by automatic recoveringproperties (such as mechanical, electrical and aesthetic properties),and thus extending the lifetime of the coating. In embodiments,self-healing materials can be applied to make “self-healing” coatings,including, for example, microencapsulation and the introduction ofreversible physical bonds such as hydrogen bonding, ionomers andchemical bonds (Diels-Alder chemistry). Microencapsulation is the mostcommon method to develop self-healing coatings. By using theaforementioned materials for self-healing in coatings, it was proventhat microencapsulation effectively protects the metal against corrosionand extends the lifetime of a coating.

In embodiments, the self-healing material may be in the form of acementitious material. Cementitious materials have a natural ability toself-heal, which can be improved by the integration of chemical andbiochemical strategies. Autogenous healing is the natural ability ofcementitious materials to repair cracks. This ability is principallyattributed to further hydration of un-hydrated cement particles andcarbonation of dissolved calcium hydroxide. Cementitious materials infresh-water systems can autogenously heal cracks up to 0.2 mm over aperiod of 7 weeks. Self-healing of cementitious materials can beachieved through the reaction of certain chemical agents. Two mainstrategies exist for housing these agents, namely capsules and vasculartubes. These capsules and vascular tubes, once ruptured, release theseagents and heal the crack damage. The self-healing ability of concretehas been improved by the incorporation of bacteria, which can inducecalcium carbonate precipitation through their metabolic activity.

FIG. 5 shows the tube structure 1 with the hole 7 in the outer tube 3 inaccordance with aspects of the disclosure. As shown in FIG. 5, once thehole 7 is formed, the fluid 9 enters the chamber 5 and comes intocontact with the SHM 11. That is, the SHM 11 is arranged within thechamber 5 (e.g., when the tube structure 1 is manufactured orassembled). In embodiments, the SHM 11 may be arranged discretely or ina continuous manner within the chamber 5. In embodiments, the SHM 11 maybe encapsulated in an encapsulating material (not shown). As should beunderstood, depending upon where the tube structure 1 is located, thefluid 9 may be a liquid (e.g., seawater) or a gas (e.g., ambient air).In some embodiments, the SHM 11 may be arranged only in portions of thetubular structure (for example, some portions of a tubular structurethat may be more susceptible to hole formation).

FIG. 6 shows the tube structure 1 after the fluid 9 has come intocontact with the SHM 11 in accordance with aspects of the disclosure. Asshown in FIG. 6, with this exemplary and non-limiting embodiment, inthose regions where the fluid 9 contacts the SHM 11, the SHM 11 reactsto form a first solidified section (or SS) 13. In accordance withaspects of the disclosure, the first SS 13 is operable to conform to theinner surface of the outer tube 3 and fill in the hole 7, creating aseal (e.g., a vacuum-tight seal) in the hole 7, and thus repair the hole(at least temporarily).

FIG. 7 shows how, in embodiments, the first SS 13 is operable to furtherexpand within the chamber 5 to additionally be in contact the outersurface of the inner tube 2 to provide increased structural support forthe tube structure 1 and the SS 13 at the hole 7 in accordance withaspects of the disclosure. In other words, in embodiments, the SHM isconfigured such that upon activation, the solidified section 13 expandsto occupy a volume of the tube structure. In accordance with furtheraspects of the disclosure, the SS 13 can provide further structuralsupport to the outer tube 3 when fully expanded and solidified withinchamber 5.

FIG. 8 shows a further tube structure configuration comprising aplurality of chamber separators, comprised of at least a first chamberseparator (CS) 15 and a second chamber separator (CS) 17. In accordancewith aspects of the disclosure, the plurality of chamber separatorsprovides a number of discrete chambers, which compartmentalizes anysustained damage to the tube structure to the affected discretechamber(s). Additionally, the plurality of chamber separators may act assupports between the inner and outer tubes 2, 3 to maintain theintegrity of the chamber 5.

In accordance with aspects of the disclosure, the separators areoperable to prevent premature reaction of the SHM 11. For example, if ahole occurs in the outer tube 3, the inflow of fluid through the hole(prior to the formation/expansion of the solidified section) will beconstrained by the respective chamber separators. As such, the SHM 11arranged in other regions of the tube will not be impacted by the inflowof fluid 9, and will not form solidified sections (i.e., will remainunreacted). Accordingly, if a hole subsequently forms in one of theseother regions, the SHM 11 in that region (which has not yet been reactedto repair the previously-formed hole) is able to form a solidifiedsection in that region so as to seal the subsequently-formed hole.

Depending on the tube manufacturing process, a plurality of SHM 11 maybe, for example, injected, sprayed, arranged, or inserted by any othersuitable approach in the chamber 5 within the spaces between theplurality of chamber separators 15, 17 and the inner and outer tubes 2,3. In other contemplated embodiments, a robot (for example, similar tothat disclosed in commonly-assigned application Ser. No. 15/374,230,entitled “Method and System for Forming Laser Beam Weld Lap-PenetrationJoints,”) may be configured to traverse internal passages (e.g., thechambers formed by the chamber walls) and position, spray, lay, and/orinsert the SHM 12. As shown in FIG. 8, the plurality of SHM comprises atleast a first SHM 12.

FIG. 9 shows the tubular structure 1 with the hole 7 in the outer tube3. As shown in FIG. 9, the fluid 9 travels through the hole 7 and comesinto contact with the first SHM 12, in accordance with aspects of thedisclosure.

FIG. 10 shows the first SHM 12 reacting to the fluid 9 in accordancewith aspects of the disclosure. As shown in FIG. 10, upon reacting withthe fluid 9, the first SHM 12 is operable to expand and solidify, so asto form a solidified section (SS) 14.

FIG. 11 shows how the SS 14 is operable further expand to fill in andclose the hole 7 in the outer tube 3. In accordance with aspects of thedisclosure, the SS 14 forms a fluid-tight seal to prevent further fluid9 from entering the chamber 5.

FIG. 12 shows how the solidified section SS 14 may be configured tocontinue to expand and fill up an entire area between the hole 7 in theouter tube 3, the first and second chamber separators 15, 17, and theinner tube 2 (at least for a length of the tube sufficient to close thehole 7) in accordance with aspects of the disclosure. In other words, inembodiments, the SHM is configured such that upon activation, thesolidified section 14 expands to occupy a volume of a discrete chamber(i.e., an entire cross-sectional area for some length) of the tubestructure. In accordance with further aspects of the disclosure, the SS14 can provide further structural support to the outer tube 3 when fullyexpanded and solidified within the particular discrete chamber.

While the exemplary embodiment of FIG. 8 depicts how a tube structure 1may be segmented into discrete chambers around the circumference of theinner tube 2, the disclosure contemplates that the tube structure 1 mayadditionally (or alternatively) be segmented into discrete chambersalong the length tube structure. For example, a tube structure mayinclude a plurality of longitudinal chamber separators within aparticular section of the tube structure structured and arranged toprovide a plurality of discrete tube chambers along the longitudinallength of the tube section. Alternatively, the disclosure contemplates aparticular tube section (e.g., a discrete tube section) having nolongitudinal chambers formed therein.

In embodiments, the SHM may be arranged in the chamber prior to theforming of the chamber. That is, for example, the SHM may be secured(e.g., with adhesive) to the outer wall of the inner tube 2, andsubsequently, the outer tube 3 may be arranged around the inner tube. Inother contemplated embodiments, the SHM may be inserted into the alreadyformed chamber (e.g., for a discrete section of tube). In furtherembodiments, the SHM may be arranged in the chamber when forming and/orwelding the chamber separators.

In embodiments, the SHM may be reactable through contact with theincoming fluid to form the solidified section. For example, the SHM maybe configured to react with water. While arranged in the chamber 5, theSHM is maintained in a dry condition. If a hole is formed in the outertube 3, water enters through the hole, contacts and reacts with the SHM,such that the SHM undergoes, e.g., a chemical reaction, to form thesolidified section. In embodiments the SHM may be arranged in thechamber 5 when the tube is manufactured. In such embodiments, the SHMmay be covered with a removable protective layer during assembly of thetube structure, and during placement of the tube structure along thetube transportation path. The removable protective layer is structuredand arranged to prevent contact between the SHM and the water. Aftermanufacture and assembly, but, for example, prior to the addition of anext tube section, the protective layer can be removed so that the SHMis in a ready-to-be-activated state.

In further embodiments, the SHM may be maintained within an enclosure(e.g., a vessel or a capsule) or under a protective layer that isstructured or configured to break and/or open and/or dissolve withcontact from the incoming fluid. In other contemplated embodiments, theformation of a hole may cause a shockwave in the chamber that causes theenclosure to break, thus releasing the SHM within the chamber.

In further contemplated embodiments, the SHM may comprise an epoxy-typesealant formed by a reaction of two materials. That is, instead of theSHM reacting with the fluid of the uncontrolled environment to form thesolidified section, the disclosure contemplates the fluid of theuncontrolled environment may react with (e.g., dissolve) the enclosureholding the two materials separate from one another, such that thesematerials are able react with each other to form the solidified section.

It should be understood that while SHM may refer to materials that healthemselves, in the context of the present disclosure, SHM also refer tomaterials that are operable seal holes in adjacently arranged materials(e.g. the tube wall).

While holes occurring in the inner tube 2 may be of less concern in thecontext of a high-speed transportation system (as the low-pressureenvironment would likely be maintained by the outer tube 3), thedisclosure contemplates that multiple self-healing materials may beutilized, wherein one self-healing material (SHM) is operable to reactwith the fluid of the outside uncontrolled environment, and anotherself-healing material is operable to react with the fluid of the insidecontrolled environment. In such an embodiment, it may be necessary tomaintain a pressure in the chamber 5 at a lower pressure than thecontrolled environment so that a hole formed in the inner tube willcause a fluid flow from within the controlled environment to the chamber5. Thus, if a hole developed in the inner tube 2, a fluid from thecontrolled environment would flow into the chamber 5 and would reactwith the self-healing material that is operable or configured to reactwith the fluid of the inside controlled environment. In contrast, if ahole developed in the outer tube 3, a fluid from the uncontrolledenvironment would flow into the chamber 5 and would react with theself-healing material that is operable or configured to react with thefluid (e.g., seawater or ambient air) of the uncontrolled environment.

Additionally, in embodiments the self-healing material may be configuredto seal multiple holes. For example, a projectile may form a hole inboth the outer tube and the inner tube, and the self-healing materialmay be configured and arranged to solidify and/or expand to seal bothholes. In further contemplated embodiments, two holes may be formed, forexample, in the outer tube, e.g., in close proximity to one another. Theself-healing material may be configured and arranged to solidify and/orexpand to seal both holes in the outer tube.

While the discussed embodiments include both an inner tube and an outertube with at least one chamber arranged there between, wherein theself-healing material is arranged in the at least one chamber, thedisclosure contemplates the use of a self-healing material with a singletube structure. For example, the self-healing material may be arrangedas a coating on an inner wall of the tube. Upon contact with a reactingmaterial (e.g., a foreign fluid entering through a hole in the tube),the coating is operable to solidify and form a solidified section thatseals the hole. While the two tube embodiment discussed above mayutilize the walls of the inner tube and the outer tube to constrainexpansion of the solidified section, with the one tube embodiment,expansion may be less constrainable. As such, with such single tubeembodiments the self-healing material may be configured to have a lowerrate of expansion.

One or more embodiments of the disclosure may be referred to herein,individually and/or collectively, by the term “invention” merely forconvenience and without intending to voluntarily limit the scope of thisapplication to any particular invention or inventive concept. Moreover,although specific embodiments have been illustrated and describedherein, it should be appreciated that any subsequent arrangementdesigned to achieve the same or similar purpose may be substituted forthe specific embodiments shown. This disclosure is intended to cover anyand all subsequent adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the description.

The above disclosed subject matter is to be considered illustrative, andnot restrictive, and the appended claims are intended to cover all suchmodifications, enhancements, and other embodiments which fall within thetrue spirit and scope of the present disclosure. Thus, to the maximumextent allowed by law, the scope of the present disclosure is to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing detailed description.

Accordingly, the novel architecture is intended to embrace all suchalterations, modifications and variations that fall within the spiritand scope of the appended claims. Furthermore, to the extent that theterm “includes” is used in either the detailed description or theclaims, such term is intended to be inclusive in a manner similar to theterm “comprising” as “comprising” is interpreted when employed as atransitional word in a claim.

While the disclosure has been described with reference to specificembodiments, those skilled in the art will understand that variouschanges may be made and equivalents may be substituted for elementsthereof without departing from the true spirit and scope of thedisclosure. While exemplary embodiments are described above, it is notintended that these embodiments describe all possible forms of theembodiments of the disclosure. Rather, the words used in thespecification are words of description rather than limitation, and it isunderstood that various changes may be made without departing from thespirit and scope of the disclosure. In addition, modifications may bemade without departing from the essential teachings of the disclosure.Furthermore, the features of various implementing embodiments may becombined to form further embodiments of the disclosure.

While the specification describes particular embodiments of the presentdisclosure, those of ordinary skill can devise variations of the presentdisclosure without departing from the inventive concept. For example,while the disclosure refers to tubular structures and depicts circulartubular structures, the disclosure contemplates other (e.g.,non-circular) tubular structures, such as oval tubular structures,and/or rectangular tubular structures. Additionally, other “tubular”structures may include other shapes, such as triangular, hexagonal,pentagonal, octagonal, and other “unique” cross-sectional shapes.

Insofar as the description above and the accompanying drawing discloseany additional subject matter that is not within the scope of the claimsbelow, the embodiments are not dedicated to the public and the right tofile one or more applications to claim such additional embodiments isreserved.

We claim:
 1. A tubular structure comprising: an outer tube; an innertube arranged within the outer tube; at least one chamber formed betweenthe outer tube and the inner tube; and at least one self-healingmaterial arranged in the chamber, wherein the self-healing material isconfigured to solidify and/or expand upon contact with a reactingmaterial.
 2. The tubular structure of claim 1, further comprising atleast two chamber separators, wherein the at least one chamber comprisesa plurality of chambers formed by the at least two chamber separators.3. The tubular structure of claim 2, wherein the chamber separatorsextend in a radial direction between the inner tube and the outer tubeand extend longitudinally along the inner tube.
 4. The tubular structureof claim 2, wherein the chamber separators extend in a radial directionbetween the inner tube and the outer tube and extend circumferentiallyalong the inner tube.
 5. The tubular structure of claim 2, wherein theat least one self-healing material is arranged in discrete portions ineach of the plurality of chambers.
 6. The tubular structure of claim 1,wherein the reacting material is at least one foreign fluid.
 7. Thetubular structure of claim 1, wherein the reacting material is arrangedin proximity to the self-healing material, while being maintainedisolated from the self-healing material by an isolating material.
 8. Thetubular structure of claim 7, wherein the isolating material is operableto dissolve, degrade, disintegrate, and/or breakdown upon contact with aforeign fluid.
 9. The tubular structure of claim 1, wherein the innertube is concentrically arranged within the outer tube.
 10. The tubularstructure of claim 1, wherein the at least one self-healing material isstructured and arranged to be contacted with a foreign fluid enteringthe at least one chamber through a hole formed in a wall of the outertube, and upon the solidification and/or expansion of the self-healingmaterial, forms a solidified section that seals the hole.
 11. Thetubular structure of claim 10, wherein the at least one self-healingmaterial is configured such that the solidified section formed therefromexpands to contact both the outer tube and the inner tube.
 12. Thetubular structure of claim 2, wherein the at least one self-healingmaterial is configured such that a solidified section formed therefromexpands to contact both the outer tube and the inner tube and aplurality of chamber separators.
 13. The tubular structure of claim 1,wherein the self-healing material is encapsulated in an enclosingmaterial.
 14. The tubular structure of claim 1, wherein the at least oneself-healing material is structured and arranged to be contacted with aforeign fluid entering the at least one chamber through a hole formed ina wall of the inner tube, and upon the solidification and/or expansionof the self-healing material, forms a solidified section that seals thehole.
 15. The tubular structure of claim 1, wherein the self-healingmaterial comprises at least one of polymers, elastomers, metals,ceramics, cementitious materials, and grout materials.
 16. A method offorming a tubular structure comprising an outer tube, an inner tubearranged within the outer tube, and at least one chamber formed betweenthe outer tube and the inner tube, the method comprising: forming the atleast one chamber; and arranging at least one self-healing material inthe at least one chamber, wherein the self-healing material isconfigured to solidify and/or expand upon contact with a reactingmaterial.
 17. A method of sealing a hole in a tubular structurecomprising an outer tube, an inner tube arranged within the outer tube,at least one chamber formed between the outer tube and the inner tube,and at least one self-healing material arranged in the at least onechamber, wherein the self-healing material is configured to solidifyand/or expand upon contact with a reacting material, the methodcomprising: contacting the self-healing material with the reactingmaterial such that the self-healing material solidifies and/or expandsto form a solidified section; and sealing the hole with the solidifiedsection.
 18. The method of claim 17, wherein the contacting theself-healing material with the reacting material occurs by the reactingmaterial flowing through the hole.
 19. The method of claim 17, whereinthe contacting the self-healing material with the reacting materialcomprises: a foreign fluid entering the at least one chamber through thehole; dissolving, degrading, disintegrating, and/or breaking down aisolating material arranged between the self-healing material and thereacting material using the foreign fluid entering through the hole sothat the self-healing material interacts with the reacting material. 20.The method of claim 17, wherein the hole is formed in the outer tube.21. The method of claim 17, wherein the hole is formed in the innertube.